<?php
$tests = array(
    "42",
    "1337",
    "fbea",
    "02471",
    "0b10100111001",
    "1337e0",
    "not numeric",
    array(),
    9.1
);

foreach ($tests as $element) {
    if (is_numeric($element)) {
        echo "'{$element}' is numeric", PHP_EOL;
    } else {
        echo "'{$element}' is NOT numeric", PHP_EOL;
    }
}
?>